If you are considering alternative and clean sources of energy for your off-grid cabin, RV, or home then may come across a 3 kW Solar system as an option.
You might be wondering if it is worth the investment and what kind of performance in terms of runtime you can expect when using such a system.
So in this guide, I discuss whether a 3 kW solar system is worth it, what savings you can expect from it, typical configurations for solar panels and batteries you can consider, and what sort of runtimes you can expect with such a system.
Is a 3 kW Solar system Worth It?
The estimated payback period for a 3 kW system without subsidies is about 7-10 years assuming an electricity tariff of 13 cents per kWh and even then at the point, you will probably need to invest in a new set of batteries.
This assumes an estimated cost of USD 4,000 plus installation (at the time of writing this post) for a complete solar system including solar panels, a charge controller, inverter, and a set of batteries.
That said, solar systems are generally low maintenance compared to a generator, for instance, produce clean energy from the sun, and are silent too with minimal running costs.
If these benefits are important to you and budget is not an issue then it is probably worth it.
How Much are the Energy Savings from a 3 kW Solar System?
The estimated monthly energy savings from using a 3 kW Solar system are USD 50.
This assumes that the solar system generates an average of 12kW per day and 360 kW per month at a tariff of 13 cents per kWh.
- Daily energy savings (USD)= 12 kWh x 13 cents per kWh = USD 1.56
- Monthly energy savings (USD)= 12 kWh per day x 30 days x 13 cents per kWh = USD 1.56 = 46.8 kWh
How Many Batteries Can You Use for a 3 kW Solar System?
A location that receives about 4 hours of sunshine can generate about 12kWh of electricity a day from its 3 kW solar system.
The question of how many batteries you can use has a bearing on the available budget of the system and how much of the generated energy you plan to store in the batteries.
This, therefore, implies there are several possible battery setups you can use.
Below we consider possible battery configurations you can use to store 4.8 kWh of energy (40% of the generated budget) to manage investment in the battery bank.
With AGM or GEL Batteries
For a 4,800 Wh battery Bank, you can use:
You can connect the 4 pcs of 12V 200 Ah AGM or GEL batteries in series for a 48V bank.
With Lithium Batteries:
For a 4,800 Wh battery bank, you can use:
You can connect the 4 pcs of 12V LiFePO4 batteries in series for a 48V bank.
What Can a 3 kW Solar System Run?
A 3 kW solar system complete with battery bank and inverter can run several appliances including lights, TVs, laptops, low power tools, microwave, washing machine, coffee pot, air conditioner reliably provided:
- The inverter’s continuous and surge power consumption is not exceeded.
- The total daily energy consumption of the connected appliances does not exceed the energy generated and stored by the batteries.
Drawing more power from the inverter than it can handle results in an overload condition which usually shuts down the inverter and in extreme cases can damage it.
Here is an indicative list of appliances (with estimated runtimes that you expect from a 3 kW solar system).
This assumes daily storage of about 4.8 kWh.
- Fridge: 250w for 10 hours =250 x 10 = 2,500 watt hours
- Lights: 10 watts, 9 pcs running for 9 hours = 10 x 9 x 9 = 810 watt hours
- TV: 50 watts, 1 pc running for 5 hours = 50 x 1 x 5 =250 watt hours
- Laptop: 40 watts, 1 pc for 5 hours = 40 x 1 x 5 = 200 watt hours
- Washing machine: 250 watts for 3 hours = 250 x 1 x 3 = 750 watt hours
Total = 4,510 – watt hours total power consumption is 680 watts which can be handled by a 3,500 watt rated inverter.
You could double the battery capacity to have the appliances running for a longer time but keep in mind that this increases your investment cost.
How Many Solar panels are in a 3 kW Solar system?
You can have 16 pcs of 195 W Solar panels ( 3 strings in parallel of 4 solar panels connected in series) for a 48V Solar System.
This is just one of several possible configurations you can adopt for a 3 kW Solar system.
How big is a 3 kW Solar system?
Assuming the 195 W solar panel dimensions are about 58 by 26 inches then you can expect the 16 pcs of 195 W solar panels to take up about 194 sq. ft or 18 sq. m.
The roof size may be more or less depending on the efficiency of the solar panels. More efficient solar panels take up less roof space.
Can a 3 kW Solar System Run an AC?
A 3 kW solar system can run an AC provided its continuous and surge power rating does not exceed the power inverter’s handling capabilities.
If the solar system is bundled with a 3.5 kW inverter, then the power requirements of the AC typically should not exceed a continuous power draw of about 2.8 kW (running at 80% of its capacity) and a surge capacity rating of 7 kW.
Make sure that the AC is rated for a 115V for it to work with the 110/115V inverter output.
Consult the AC’s technical specification guide to confirm its continuous and surge power ratings
Can a 3 kW Solar System Power a Whole house?
It depends on the energy needs of the house. The United States Energy Information Administration (USEIA), estimates the daily energy consumption of an average house in the US, in 2020 to be about 30 kWh.
A 3 kW solar system only generates about 12 kWh daily (40% of the estimated average energy needs of a US household).
So if the energy demand for the house is below or about 12 kWh then it will likely meet the energy requirements of the house otherwise you’ll likely need a larger solar system.
Keep in mind though that you need to consider its peak energy demand too to be sure.
3 kW Solar system |How Much Electricity it Generates
Daily electricity output
A 3 kW solar system can generate an estimated 9 – 12 kWh ff energy per day assuming your location receives about 3-4 hours of sunshine.
Monthly electricity output
The monthly electricity output of a 3 kW solar system is can be expected to range between 270 – 360 kWh of energy per day assuming your location receives about 3 – 4 hours of sunshine.
To get as much power as possible, the solar panels should be angled to face the sun as much for as many hours as possible with no shadows cast on the panels.
Clean the panels to remove any dust or other debris that can obstruct the sun from reaching the panels for maximum power output.
If you are looking to save money, you have access to the grid and there are no subsidies then from a financial savings standpoint, it is likely not worth it to invest in a 3 kW Solar system unless benefits the use of clean energy, no noise pollution is important to you.
Should you decide to invest in one, while there are several possible battery bank configurations, you can consider for a 4,800 kWh battery bank (one of the possible options available).
You can connect the 4 pcs of 12V 200 Ah AGM or GEL batteries in series for a 48V bank or 4 pcs of 12V LiFePO4 batteries in series( 48V bank).